PRINCE WILLIAM: I've been trying to rest this (INAUDIBLE) past and I'm looking forward to seeing what the future holds.

O'BRIEN: Will this time be different?

(On camera): April 29th, 2011, Westminster Abbey, the location of the much anticipated wedding of Prince William and Catherine Middleton. Ironically, it was this abbey where his mother Princess Diana was laid to rest in 1997. And in the years between that memorial and this celebration, the legacy of Diana, and the tragedy of her life were critical in Prince William's journey to the altar.

JULES KNIGHT, FRIEND OF WILLIAM AND KATE: I think that she's probably never far from his mind. I think he thinks about her every day.

O'BRIEN (voice-over): Jules Knight says he's been friends with Prince William for more than a decade.

(On camera): Did he give any inklings about the relationship he had with his mother?

KNIGHT: I think it was evidenced to everybody that they were incredibly close. He's mentioned on a number of occasions that she was never far from his mind.

William going through this sort of right of passage where you're growing up and you don't have that incredibly important figure in your life. It must be incredibly difficult because you think, oh, I wish my mom was here for that.

O'BRIEN (voice-over): Rights of passage that were not easy, given the difficulty of growing up in a broken home.

KNIGHT: He went through the pain of the divorce. He then went through the agony of his mother's death and it must have had an incredibly profound effect upon the way that he then wanted to conduct his own relationships.

O'BRIEN: Despite Diana's best efforts her sons grew up in the same kind of contentious homes she did.

Diana was just 7. Half William's age when her family was also shattered by a bitter divorce and nasty custody battle.

(On camera): So this is the room where Diana was born.

MARY CLARK, PRINCESS DIANA'S FORMER NANNY: Yes, this is where Diana was born.

O'BRIEN (voice-over): Mary Clark was Diana's nanny.

CLARK: She said I will never, ever marry unless I'm really in love because if you're not in love, you're going to get divorced and I never intend to be divorced.

CHRISTOPHER ANDERSON, AUTHOR, WILLIAM AND KATE: She never really had a happy centered home life. I think she spent all of her adult life searching for that.

O'BRIEN: Christopher Andersen who's written several books about the royal family says that in Diana's search for a happy home life, she had a unique confidant. William.

ANDERSON: As a small boy, William witnessed a lot of this. And William because sort of the fixer. And here's this little boy when his mother locks herself in the bathroom after an argument with Charles. And she's sobbing and he's just little, you know, 7-year-old William slipping tissues under the door and saying I hate to see you sad, mommy.

He was always somebody who's just very, very sensitive to other people's feelings. So he walks into this situation with Kate. He meets Kate and Kate exposes him to a happy family for the first time.

O'BRIEN (on camera): Stability?

ANDERSON: Stability.

O'BRIEN (voice-over): A happiness and normalcy that Diana was desperate for her sons to find. Her close friend Lana Marks remembers.

LANA MARKS, PRINCESS DIANA'S FRIEND: She wanted to have them experience as much of a normal life or exposure to a normal life as possible. She also wanted to make sure that they shared enormous love.

O'BRIEN: But finding love would not be easy for a prince, the heir apparent to the British monarchy. William lived with a kind camera lens keenly focused on his every move. A spotlight that followed him from a very early age.

KEN WHARFE, FORMER ROYAL BODYGUARD: I remember William's first day of pre-prep school in north London.

O'BRIEN: Ken Wharfe was Diana and the prince's bodyguard for more than eight years.

WHARFE: Diana said to him, now William, when we get to school, there'll be lots of photographers. And he said, you know, I don't like photographers in this sort of very just William-esque way.

And we arrived at the school and there outside the school about 120 or 130 photographers waiting for William's first day of school. What she was trying to say to William on his first day of school, look, you've got to live with this. You're going to get this for the rest of your life. He now knows that.

O'BRIEN: It would be something that William would learn to live with.

UNIDENTIFIED REPORTER: Princess Diana has died.

O'BRIEN: That is, until his mother's death.

UNIDENTIFIED REPORTER: The French Police criminal unit is going --

O'BRIEN: An accident that many, including William, blamed on the aggressive paparazzi.

WHARFE: I did think he drew a picture of, I didn't like them, and wasn't prepared even to debate the subject.

O'BRIEN: Not long after the crash, the palace and the press forged a gentleman's agreement giving both William and his brother Harry the privacy to grow up. The world got quick glimpses, though. All carefully choreographed by the palace.

But aside from that, William seemed to shun the media. And with that distance, he was able to grow up and sew his wild oats.

ANDERSON: He began dating some of the more beautiful titled ladies. He tried an online romance with Britney Spears at one point. It never really got off the ground.

O'BRIEN: It was in the year between Eton and going to university in Scotland that William worked in Kenya and met the woman many say was his first love, Jecca Craig.

ANDERSON: They became romantically involved. He staged a mock engagement. It was kind of a tongue-and-cheek kind of thing. But you know he asked her to marry him jokingly at the foot of Mt. Kenya.

O'BRIEN: A place that will ironically play a key role in his engagement to Kate Middleton. But that's later.

First, William would have to meet Kate. And that would happen at St. Andrews University.

(On camera): Why would he go there? I mean all the other royals had gone there.

KNIGHT: I think it was an attempt to get away from the public eye to some extent. I met him pretty much as soon as we arrived. And incredibly quickly, this group of friends formed.

O'BRIEN (voice-over): Among his small intimate group of friends, a young woman whose background was anything but royal.

ANDERSON: Not long after William invited a number of friends to his dormitory room, she did this kind of automatically did this awkward curtsy and he reacted by simply spilling his drink on himself because he realized he would do things like this to put people at ease. And from that point on, they became friendly.

O'BRIEN: In contrast to Kate, most of Williams' friends were aristocratic with considerable royal connections. Connections that his mother knew throughout her life.

Princess Diana grew up in the shadows of the royal family. Her grandmother was a confidant to the queen. Diana was an aristocrat through and through.

Kate was what the British call a commoner. She grew up a world away from country estates and Buckingham Palace.

JOHN HAILEY, INNKEEPER: It's in an area of outstanding natural beauty.

O'BRIEN: John Hailey is an innkeeper at Bucklebury, Berkshire. A small sleepy village 55 miles west of London. He met the Middletons 14 years ago when they first came into his pub, the Old Boot Inn.

HAILEY: They're very nice, just very nice family, down to earth. Fairly, easy going, relaxed. Yes, a lovely family.

ANDERSON: They were not wealthy.

O'BRIEN (on camera): They were solidly middle class?

ANDERSON: Absolutely. Solidly middle class. Hard working folks.

O'BRIEN (voice-over): Carol Goldsmith and Michael Middleton met while working for a British airline. They married in 1980. Kate was born in 1982. Her early years were as ordinary as you can imagine. Baptized at a picturesque chapel, she was a brownie and liked to perform in plays and musicals. A simple life in the quiet English countryside.

Friends say the closest the Middletons got to the royals was watching stories about them on TV.

UNIDENTIFIED REPORTER: A marriage that captivated not just --

ANDERSON: When Charles married Diana in 1981, like the rest of the planet earth, they were glued to the set and watching every minute of it. Of course Carol dreamed someday of having her daughter enter that life but it seemed an impossible, I'm sure.

O'BRIEN: Impossible that is until Carol Middleton, a stay-at-home mother stumbled on to a very lucrative career.

ANDERSON: She had a talent for making goody bags for children's parties. And she really spun it into this Internet empire. Now the family quickly moved up the ladder. Within a couple of years, they were making millions of dollars a year. Hence, Kate was sent to some of the big most expensive and prestigious schools.

O'BRIEN (on camera): Kate was 13 years old when she arrived at this exclusive school in the English countryside called Downe House, a school that catered to nobility and aristocracy. When she stepped foot on campus, she was outgoing girl who loved sports and learning. But soon that'll all change.

ANDERSON: She became the victim of the mean girls in the school. There was malicious gossip about her background because she was one of the very girls from a working class background attending that school.

O'BRIEN (voice-over): Many said Kate became miserable, shy and withdrawn, much like Diana when she first went to boarding school.

PENNY WALKER, PRINCESS DIANA'S FORMER MUSIC TEACHER: She was very shy, though, I didn't really notice her.

O'BRIEN: Penny Walker, Diana's music teacher at the West Heath School remembers.

WALKER: It was -- full of unrests in her home life. That often affects children in their work.

O'BRIEN (on camera): Were her bad grades troubling to her? WALKER: I think immensely troubling. And I think she tried really hard. But I think her concentration was elsewhere.

O'BRIEN: On what?

WALKER: Family.

O'BRIEN (voice-over): With absentee parents, Diana was forced to struggle through on her own. Many say that the insecurity fostered in these years would stay with her for the rest of her life.

It was very different for Kate Middleton, though. Her parents immediately switched their daughter to another nearby boarding school, Marlborough College. And the lessons she learned would make her stronger.

UNIDENTIFIED MALE: Marlborough was a big school. I was there from age of 13 to 18.

O'BRIEN: Ali Baines (ph) was a student with Kate at Marlborough. Now a performer with the singing group Lake.

BAINES: Boarding schools, if they're not happy, are miserable. There's very, very few in between.

O'BRIEN: And Kate's first day at Marlborough wouldn't be easy.

ANDERSON: All the boys are on the other side of the dining hall and they hold up pieces of paper. And on those pieces of paper are numbers. She asked what's that all about, well, the boy always rate the girls on their looks.

O'BRIEN (on camera): What was the numbers?

ANDERSON: No guy rated her above -- at two.

O'BRIEN: Two out of 10.

ANDERSON: Two out of 10.

O'BRIEN (voice-over): Carol Middleton once again stepped in.

ANDERSON: Her mother actually set out to transform her. She combed out her lush chestnut hair. She got her wearing make-up for the first time and so when she reappeared in school, it was a new person.

O'BRIEN (on camera): Kate became one of the most popular girls here at Marlborough. A tremendous athlete, a serious student but she also had a reputation as having a bit of a wild side. One friend said Kate frequently liked to moon the boys from her dorm room window. And it earned her the nickname Kate Middlebum.

BAINES: It was reasonably happy school. It was quite fun and she was -- she was a very pretty girl, yes.

O'BRIEN (voice-over): Yet Kate didn't date much. And despite her denials, many who knew her then insist she set her sights higher than prep school classmates.

ANDERSON: I talked to too many friends who said, yes, she always had this picture over her bed in her dormitory. It was a picture of William. So she did have her sights set on him.

O'BRIEN: Eerily reminiscent of another girl, decades earlier.

WALKER: She was always known to adore Prince Charles. And her little bedroom cubicle had pictures of him all over it.

O'BRIEN: While Diana knew Charles from the royal circles they both traveled in, Kate didn't know William at all. But she nearly had a chance in the winter of 2000. After her graduation from Marlborough both Kate and William traveled to Chile with the same youth volunteer group. But it turns out at different times.

Malcolm Sutherland was their leader.

MALCOLM SUTHERLAND, LEADER, RALEIGH INTERNATIONAL: I think it's incredible from the start that the fact that William and Kate they didn't even know each other.

O'BRIEN: They just missed each other. On two separate trips, just weeks apart, they helped build buildings, teach English, even clean toilets in the same small town in Chile.

SUTHERLAND: Kate's tough. She's a sporty, fit lady. She knew what she was about. She knew how to look after herself.

O'BRIEN: While Kate missed William that winter he then started preparing for university. And this time, she wouldn't miss her prince.

ANDERSON: Originally Kate wanted to go to Edinburgh University. When it was announced by the palace that William would be attending St. Andrews University, enrollment among women in St. Andrews jumped overnight by over 40 percent.

ANDERSON: In Kate's case, did she nudge her toward a relationship with the future king of England? Yes. And why not? You know? Because by putting her in proximity to William, magic happened.

O'BRIEN (voice-over): A close friendship takes a passionate turn, when we come back.

(COMMERCIAL BREAK)

O'BRIEN: It's a night that rocked St. Andrew's University every year. A night that eight years ago shook up Prince William and Kate Middleton's friendship forever.

March, 2002. The annual charity fashion show called "Don't Walk." A lingerie show where the models were nearly naked. Kate was no exception.

Jules Knight was in the audience in that night with Prince William.

KNIGHT: She looked great.

O'BRIEN (on camera): And were people stunned?

KNIGHT: Definitely. She wasn't what you call a kind of risque girl. She was pretty safe bet, quite conservative really in the way that she dressed and the way that she acted.

And here she was not wearing that much, looking amazing. And all the guys, all of a sudden realized, wow.

O'BRIEN: Kate is hot.

ANDERSON: Kate is hot. Yes. He really wanted to start something. It was -- that was the point that William pursued her romantically and very quickly.

O'BRIEN (voice-over): Up until that night, William and Kate's friendship had been purely platonic. Prince William remembers fondly.

PRINCE WILLIAM: We were friends for over a year first. And it just sort of blossomed from then on.

O'BRIEN: They bonded over their shared major of art history, early morning swims in the campus pool and their sense of humor.

PRINCE WILLIAM: She's got a really naughty sense of humor, which kind of helps me because I've got a really dry sense of humor, so it was good fun, we had a really good laugh and then things happened.

KNIGHT: You know you'd often see them sitting -- on a radiator at a house party and he had a bottle of JD by him and was sort of drinking away and they both sort of conduct their relationship and get to know each other as friends.

O'BRIEN: Life with Prince William was quite the party.

KNIGHT: I remember, you know, we walked out of a pub. W were quite drunk and we were walking down the street, about 10 of us. I saw a pellet gun on the floor. I picked it up and I started waving it around. And then he grabbed it out of my jacket pocket, and he was holding it in the air, and suddenly even in my drunken state, I was like this is probably not a good idea.

What does this look like from behind? And I remember looking behind and there were these bodyguards looking incredibly agitated like what the hell is going on.

O'BRIEN: But Kate always managed to stay in control. Richard Denim was another friend at St. Andrews.

RICHARD DENIM, FRIEND: I wouldn't say that she was a particularly flighty, over-excitable type person. Very measured. Very controlled. That is perfect. Because you don't want someone who's going to be falling out of the king's road face down wasted sort of these sessions.

O'BRIEN: William came to rely on Kate in good times and in bad.

CHARLES WARREN, PRINCE WILLIAM'S LECTURER: He had all the same stresses and pressures as every student does.

For some people --

O'BRIEN: Charles Warren was one of William's lecturers at St. Andrews.

WARREN: He was panicking about approaching deadlines and, you know, struggling with some of it like -- you know, most of my students do.

ANDERSON: That first year was really tough for William. He felt completely isolated from his friends and his family. He was so desperately unhappy that he after the first year he was determined to leave. And it really was Kate who talked him into staying.

She said look, we'll both stick it out together. And if at the end of sophomore year we feel the same, we'll both leave.

O'BRIEN: They stuck it out, though, and in their second year moved into this flat together with a couple of other friends.

PRINCE WILLIAM: It sort of blossomed from there really which is -- we saw more of each other, you know, hang out a bit more and did stuff. So yes.

MIDDLETON: You like my cooking?

PRINCE WILLIAM: Your cooking is all right. It's been better.

O'BRIEN: And it was in the spring of that year living together, 2002, that Kate hit the lingerie runway and William saw his close friend in a very different light. They quickly became more than just roommates.

PRINCE WILLIAM: I do generally believe now especially, you know, being friends with one another is a massive advantage.

O'BRIEN (on camera): The idea of a prince living with his girlfriend was unheard of for the House of Windsor. Diana was just 19 when she started dating Prince Charles. She lived here in a flat in London. He lived miles away in the palace. The entire courtship lasted just five months. And once they were engaged, Diana was whisked away to the Queen Mother's palace.

DR. JAMES COLTHURST, FRIEND OF PRINCESS DIANA: She lost her independence. She sent her notes like that.

O'BRIEN (voice-over): Dr. James Colthurst, a close friend of Diana's, remembers how abandoned she felt. Despite her aristocratic roots, she never seemed at home in the palace.

(On camera): Was she incredibly lonely?

COLTHURST: Very lonely.

O'BRIEN: Did she tell you that?

COLTHURST: Absolutely lonely. I think she wanted the prince to talk to her. She was expecting some romantic, you know, calls, and maybe some of that. And I think there was very, very little communication. And I think she found that very, very difficult. If that's how it was, fine, then she will, you know, bite her lip and hope it gets better after the wedding.

O'BRIEN (voice-over): It didn't. And no one knew that better than Prince William. He would do it differently. He would get to know Kate and her family intimately. In those early dating days, William would travel to Kate's home in the English countryside often.

ANDERSON: He started visiting the Middleton's home in the Bucklebury and he saw that indeed it was possible to have a happy family and a happy marriage in the Middleton's. And I think it's a big reason that Kate is the one.

KNIGHT: She's not an aristocrat. She's not somebody who's grown up in a castle or a palace. She's sort of pretty normal really. And I think he loves going to dinner around the house in Berkshire and he loves being part of something which is actually standard.

O'BRIEN: Local pub owner and Middleton friend John Hailey remembers when William would come to town.

HAILEY: He just used to come in and book a table or just walk in and people would notice him. But they'd be left alone.

O'BRIEN: But soon, that would all change. When the world discovered that these roommates were more than just friends.

Scary moments Sunday night on an Alitalia flight from Paris to Rome. An apparently agitated passenger attacked a flight attendant on Alitalia flight 329 and demanded that the flight be diverted to Tripoli, Libya.

Other flight attendants have mobilized the attacker and the plane and its 131 passengers landed safely in Rome. The attacker was taken in police custody. The flight attendant was taking to the airport emergency room for a checkup.

Flights are coming and going again at Lambert Airport in St. Louis two days after a powerful tornado tore through the city.

The clean up has just began for people living in the pathway. 750 homes were damaged. Some of them totally blown apart. Despite all that destruction, no reports of any deaths.

Those are your headlines this hour. I'm Don Lemon. The "CNN PRESENTS" special, "The Women Who Would Be Queen" returns right now.

O'BRIEN: The Swiss Alps. A holiday hot spot for the royal family. March, 2004, Prince William was about to let the world in on a secret.

ARTHUR EDWARDS, THE SUN'S ROYAL PHOTOGRAPHER: The thing is, they were sharing a house in St. Andrews. We suspected, but you never know.

O'BRIEN: For several years journalists like the "Sun's" royal photographer Arthur Edwards were left to wonder if William and Kate Middleton were a couple. Despite denials from the palace and Prince William.

But that all changed on that spring day. With paparazzi in tow, William took to the slopes with his new love.

EDWARDS: And we discovered that they were, in fact, an item.

O'BRIEN: It was ironically on the ski slopes exactly 10 years earlier that Princess Diana had begged the paparazzi for privacy for her boys.

DIANA, PRINCESS OF WALES: As a parent, could I ask you to respect my children's space?

O'BRIEN: Now, a decade later, her grown-up son took charge. Friend Jules Knight.

(On camera): Was that sort of intentional --

KNIGHT: Absolutely. Yes. I mean --

O'BRIEN: We're going to let people know?

KNIGHT: I mean if you take somebody to close to skiing which is the place that your family has been going for the last how many years, there's a pretty clear sign that he's saying to everybody, this is the girl in my life.

O'BRIEN (on camera): Newspapers ran with the story. Headlines like this, finally, "Will Gets a Girl." And for the first time, the palace didn't deny the romance.

(Voice-over): The couple would retreat behind the protective walls of St. Andrews. For the next year, they continued to live together, now without other roommates. They quietly spent more time with the royal family and it became clear to many that despite her commoner upbringing, Kate fit in, perhaps even better than Princess Diana.

ANDERSON: Kate has shown absolutely no hesitation to accompany them on their hunting trips in Balmoral, to go fishing. Diana could barely tolerate to go to these polo matches of Charles' but Kate has never missed a polo match of William's.

O'BRIEN: June, 2005. The private life William and Kate had enjoyed for nearly four years came to an end. The couple graduated from St. Andrews, left their safe, protected world behind, and plunged into a world of prying paparazzi.

KNIGHT: There were more photographers than I had seen in my life and -- I mean from around the world, like 100. And the noise of the cameras going off and the flashes was intense. It was just -- you know, unbelievable. And I think everyone realized that the game was over because the protection that they had enjoyed had finished.

O'BRIEN: In the months after graduation, the press followed them everywhere, to weddings, to polo matches. There were rumors of a break-up. Fleet Street was on fire.

And in January, 2006, it only got worse. William began his royal military training in the English countryside, leaving Kate alone in London.

ANDERSON: He was beginning his military career in essence around a lot of other young men who were going to make their lives in the military. And so there was a lot of heavy drinking going on, there was a lot of partying going on.

O'BRIEN (on camera): Was he faithful to her? With the drinking and the partying?

ANDERSON: Yes, Yes. Indeed he was. There were some indiscreet moments in bars when, you know, girls would come up to him and there'd be kissing. She handled it well. She wasn't happy with it, but she didn't end the relationship that they have.

KNIGHT: It was probably difficult on their relationship. She was having that incredible scrutiny from the press. She walked out of her flat and be besieged by 20, 30 photographers. And that really couldn't go on.

EDWARDS: And that was just chaos. They'd follow her to work, they'd stop her in the traffic with flashing through the window while she was trying to drive her car. Sitting on the wall at her office waiting for her to leave, waiting for her to arrive. That's when it's really stressful.

O'BRIEN (voice-over): All dangerously reminiscent of what happened to William's mother. Just look at the images of Diana and Kate, both taken before they were engaged.

For Diana, the pressure was often too much to bear.

EDWARDS: I remember once Diana ran into a doorway and was crying.

O'BRIEN: For Kate, it was different. Despite her young age, she seemed very smart and guarded with the press.

Kate's friend, Richard Dennis.

DENNIS: A nightclub that everyone goes to (INAUDIBLE) in south Kensington. And she was famous for always nipping into the bar, and checking her hair and makeup, before she left because she knew there were photographers waiting outside.

O'BRIEN: And while Kate publicly held her own, privately, there were serious concerns.

ANDERSON: She was not his fiancee, therefore she was not entitled technically to any kind of -- to any bodyguards. William is surrounded by bodyguards essentially at all times. And he realized that, you know, she was pretty much on her own. And he was afraid for her.

O'BRIEN: On several occasions, Kate's lawyers, the same as used by the royal family, asked newspaper editors to leave Kate alone. They even threatened lawsuits. It helped a little. But Kate was still a target just like Princess Diana. And according to Christopher Anderson, Prince William who had always had nightmares about the night his mother died now had nightmares about Kate.

ANDERSON: The accident that's happening isn't happening in the streets of Paris, it's happening in the streets of London and it's happening to Kate.

O'BRIEN (on camera): So he worries about Kate?

ANDERSON: At one point, he said, you know, I was born into this, she wasn't. And should I be subjecting her to this? So this was a constant question in their relationship.

O'BRIEN (voice-over): A question that would drive the couple apart.

(COMMERCIAL BREAK)

O'BRIEN: Times were tough for Prince William and Kate Middleton. The paparazzi in hot pursuit, six years dating, no engagement. The pressure was intense.

January, 2007, Kate's 25th birthday.

ANDERSON: The inquest into Diana's death is raging. Headlines every day about the circumstances leading to Diana's death. There's this party for Kate at Boujis, their favorite nightclub. They come out and all of a sudden they were descended on by hundreds of paparazzi.

And this huge response from bodyguards, they're shoved into the Land Rover. They speed away. But it was a moment at which it became quite obvious that it was just history repeating itself.

O'BRIEN: Lawyers for William, the palace and the Middleton's lashed out. Two newspapers responded and stopped publishing paparazzi photos. But the pressure on William and Kate was still mounting.

According to biographer Christopher Anderson, everything came to a head on Valentine's Day, 2007.

ANDERSON: She thought she'd be getting that proposal. Instead, he gave her an Van Cleef & Arpels enamel compact. They started to quarrel bitterly. She really demanded that he commit, as they say. And William wasn't ready for it. He went to his father, Prince Charles. Prince Charles said you can't keep stringing this girl along. If you're not ready to ask her to marry you, break it off. And unfortunately he listened to his father's advice.

O'BRIEN: A father perhaps trying to prevent history from repeating itself.

O'BRIEN: Mary Robertson was Diana Spencer's boss and friend when she was dating Prince Charles in 1980.

ROBERTSON: I think it was a great deal of pressure from his mother and father to get married and produce some heirs for the throne. And I think Diana was just sort of the right girl at the right time and the right place.

O'BRIEN (on camera): Insiders say Charles did care deeply for Diana but was pressured to marry before he was ready. No surprise then that their son William would not be pressured to propose.

Once spring day Kate was at work, an accessories buyer for this clothing company, when her cell phone rang. It was William.

ANDERSON: She gets this call on her cell phone, she goes into the back room. And the other employees can hear what's going on in there. And it's not pretty. I mean she's hearing the news he's breaking it off. She doesn't want this to happen. There's an emotional conversation going on. But it's the big break-up call.

O'BRIEN (voice-over): The "Sun" newspaper broke the news, April 14th, 2007. People were stunned. Kate looked grim. She packed up and headed home to her parents.

ANDERSON: She's devastated. And Kate's mother, Carol, you know, says well, fight to get him back. I mean don't -- you know don't be defeated.

O'BRIEN: Friends say it didn't take her long to rebound. St. Andrew's buddy and singer in the boy band Blake, Jules Knight.

KNIGHT: I remember having lunch with her once they -- when they'd split up. And it was so quite evident that she was -- she was being very forthright. She said, right, I'm getting on with my life. Fine. Cool. And, you know, it hasn't worked out. That's behind me. Let's move on.

O'BRIEN (on camera): How did Prince William react to the break-up?

ANDERSON: He became unglued. I mean he really started to -- you know, drinking too much, he went out with his buddies to various clubs. He was very obviously adrift emotionally. It didn't help to have him see pictures of Kate having a time of her life.

O'BRIEN (voice-over): Out on the Thames training for a cross Channel race or out on the town enjoying life as a single woman.

KNIGHT: She's a smart girl. She made sure that she wasn't going to sort of run back to him and she very was calm and level headed and strong about it. And I think he thought oh my god, what have I done?

O'BRIEN: She's going to go out, she's going to hang out with other people. And --

KNIGHT: Yes. I think he probably thought actually, I really want to be with this girl.

O'BRIEN (voice-over): Nearly three months later, there were hints the two were getting back together.

MIDDLETON: You find out things about yourself that maybe you haven't realized or I really value that time for me as well all though I didn't think it at the time.

O'BRIEN: July 1st, 2007. Princess Diana's memorial concert.

EDWARDS: Because I went to the after-concert party and they were, you know, just like normal. And I imagine that's when they -- I think made the decision perhaps that we're going to get married.

O'BRIEN: For the next three years the couple would settle into life. William in the military, Kate by his side for graduations, ceremonies and other people's weddings.

Then, October, 2010, the wait was finally over. It was a remote spot on the slopes of Mt. Kenya, Africa's second highest peak called Rutundu, a romantic lodge with a fireplace and lots of candles. Ironically, not far from where a decade earlier, William had supposedly proposed to his first love, Jecca Craig. But this time, it was Kate.

PRINCE WILLIAM: I took her up somewhere nice in Kenya and proposed.

MIDDLETON: It was very romantic. There's a true romantic in there.

UNIDENTIFIED REPORTER: You said yes obviously?

MIDDLETON: Of course, yes. Yes.

O'BRIEN: In that secluded lodge, he gave Kate a ring. They were not alone.

PRINCE WILLIAM: It was my mother's engagement ring. So I thought it was quite nice because obviously she's not going to be around to share the fun and excitement of all this. This is my way of keeping her sort of close to it all.

O'BRIEN: Ahead, ring on her finger, smile on her face. But is Kate really ready for what lies ahead?

(COMMERCIAL BREAK)

UNIDENTIFIED REPORTER: We've got a few questions.

O'BRIEN: The first time most of the world would hear Kate Middleton speak.

UNIDENTIFIED REPORTER: Could you tell us how Prince William proposed?

MIDDLETON: It was very romantic.

UNIDENTIFIED REPORTER: (INAUDIBLE)

O'BRIEN: St. James Palace, November 16th, 2010. William and Kate's engagement announcement.

MIDDLETON: It's quite a daunting prospect but (INAUDIBLE). William is a great teacher. And he'll be able to help me along the way.

O'BRIEN: The confidence of a couple who had seemingly worked it all out.

PRINCE WILLIAM: We went through a few stumbling blocks as every relationship does, but we picked ourselves up and carried on. And it's just really easy being with each other. It's really fun and I'm extremely funny and she loves that so it's been good.

UNIDENTIFIED REPORTER: (INAUDIBLE)

O'BRIEN: A bit of humor in the face of unprecedented media tension.

UNIDENTIFIED MALE: OK. (INAUDIBLE) Hang on a second.

EDWARDS: There are masses of people in there for that. You know and the questions were being fired. She coped with it very well. And he was so proud. It wasn't like his father and mother. They had about six photographers and two reporters.

UNIDENTIFIED REPORTER: Has it been a strain trying to carry out a courtship without anyone knowing?

DIANA: Yes, it has.

O'BRIEN: And painfully unconnected to her fiancee. The world caught a glimpse with Charles' awkward admission.

UNIDENTIFIED REPORTER: And I suppose in love?

DIANA: Of course.

CHARLES, PRINCE OF WALES: Barely in love, really.

O'BRIEN (on camera): Diana and Charles seemed miles apart emotionally and physically. In the months leading up to the wedding, Diana was sequestered behind the gates and the guards of this palace, the Clarence House, while Charles was on the move splitting his time between his country estate High Grove, his London residence in St. James Palace. And traveling to places as far away as Australia. Diana was always left behind.

COLTHURST: She was floating around in the Queen Mother's house without really a brief on what to do. She could have had some coaching. She could have had some -- this is about to become a world- sized job, you're going to have to learn some stuff, bits of geography, bits of history that would have been valid in the modern age, maybe even some political stuff. There was nothing.

ANDERSON: It was assumed that Diana knew what she was walking into because Diana was of their class.

O'BRIEN (on camera): She was an aristocrat.

ANDERSON: She's one of them. Yes.

O'BRIEN (voice-over): Kate would get all the coaching Diana sorely lacked.

ANDERSON: Premarital counseling from the archbishop of Canterbury. I can't think of any other royal couple less in need of premarital counseling. They worked it all out. But they're willing to go through the motions of this sort of thing.

And I think she's willing to go through the motions of being taught how to behave in front of the press. In terms of sort of specific ceremonial duties, royal etiquette, that sort of thing, yes, of course, there are certain things she's going to have to be taught.

O'BRIEN (on camera): Diana got none of that?

ANDERSON: No.

O'BRIEN (voice-over): February 24th would be Kate's first test. Her first official royal appearance in north Wales, dedicating a lifeboat. William was by her side.

EDWARDS: She learned to sing the Welch national anthem. She smiled at the right time. She coped with the wind beautifully. And she shook hands with the old and the young.

When they were launching this lifeboat, and after she poured the champagne, William bowed to her with his hands like that in acknowledgement of the fact that this was probably her first public engagement and she did it brilliantly.

O'BRIEN: Yet their lives are not dictated by palace and protocol. Unlike past royal couples, William and Kate settled far from London's palaces in a small house in remote North Wales.

ANDERSON: William is an RAF search and rescue officer. It's dangerous business. He plucks stranded hikers off mountain tops. Meanwhile Kate is kind of keeping the home fires burning at their little house in North Wales. EDWARDS: There'll be no one cooking the dinner. There'll be no one cleaning the brass. They're going to be a lot different than Charles and Diana. There's going to be no big stately home. Well, not yet anyway. He's going to be -- go to work, do his shift, come home, chill, watch TV, probably get a video, get some pizza. That's the way they're going to live their life.

O'BRIEN (on camera): It's the way Kate grew up in rural Bucklebury. Normal. Quiet. Once criticized as too common, it may be the very thing that helps keep this royal couple together.

KNIGHT: A lot of the aristocrats are probably the least able to deal with that kind of thing. They don't often have a firm grasp of what it's like to live in the real world. I'd say that she was much better equipped to deal with the pressures of royal life than the average aristocrat was.

O'BRIEN (on camera): Ironically.

KNIGHT: Ironically.

WHARFE: Unlike Diana, of course, Kate Middleton has been with William for nearly eight years. So she's had quite a lot of time to reflect and say, is this the lifestyle I want? This is what I'm going to get for the rest of my life.

In that sense, she was a considerable way ahead of Diana in understanding and knowing exactly what was coming her way.

O'BRIEN (voice-over): For William, history would not repeat itself.

PRINCE WILLIAM: It's kind of almost why I had waited this long. As I wanted to give her a chance to see and to back out if she needed to, before it got too much. Because, you know, I'm not trying to learn from lessons done in the past. And I just wanted to give her the best chance to settle in and see what -- you know what happens on the other side.

O'BRIEN (on camera): Do you think everyone has got it right this time?

ANDERSON: I think finally they've got it right. And I think it is all because of Diana. If Diana hadn't shaken things up the way she did, if she hadn't made the monarchy collectively look at itself in the mirror, and see what they were doing wrong and what they could do right, none of these changes would have happened.

And I think the true catalyst for all this change now is Kate, because in essence, you know, she's going to be the first true people's princess.

O'BRIEN (voice-over): The people's princess like Diana before her, but unlike Diana, prepared for what lies ahead. A royal couple living life on their own terms. Making their own way to the day they will become the king and queen of England.